Process of and apparatus for drying material by means of fire gases



Se t; "1, 1925. 1,551,965

G. MULLER PROCESS AND APPARATUS FOR DRYING MATERIAL BY MEANS OF FIREGASES Filed May 15, 1924 Fig.1

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idatented Sept,

hurrah star-as .llillllLLER, 0F IEEANKFORT-ON-THE-MAIN, GERMANY,ASSIGNGR TO AMERICAN 1117.113]: CORFORA'IIOIN, OF NEW" YORK, N. Y.. ACQRPORATION OF "NEVI YORK.

ZPLfilOGEfSS (325 AND APFABIA'X'US FOR DRYING:

Application filed May 15, 1924.

To aJZ whom it may concern.

Be it known that I, (inono llliimznn, a citizen of Germany, residing atFrankfortou-thei lain, in the county of llesswNassau and State ofPrussia, Germany, have invented certain new and useful Improvements inProcesses of and Apparatus for Drying Material by Means of Fire Gases,of which the following is a specification.

The present invention relates to a process of and apparatus for dryingmaterial by means of tire gases.

One object of the invention is a simplification of both the mode ofoperation and the apparatus and an increase in the efliciency thereof.

Another object of the invention is the provision of means and ways forminimizing the dangers of explosion or the destructive results thereof.

For a full understanding of the invention, the principles upon which itis based and its characteristic features reference is made to theaccompanying drawings in which:

Fig. 1 is a more or less diagrammatic representation of an apparatusembodying the invention; and

Fig. 2 is a like view showing another em bodimcnt thereof.

in Fig. 1 is shown a drying chamber 1 having;- an extendedcharging shaft1 and an outlet opening 1 which is oti'set laterail relatively to thecharging shaft. lVithin the drying chamber is disposed an inclined crate2 over which the material slides toward the outlet 1 in its downwardmovement througjh the drying chamber. The upper portion of the dryingchamber diametrically opposite the grate 2 provides a as space which isdivided into two parts by a baille 3. The upper part 3* is connected bymeans of a flue 4 to the at1nospherc, while the lower part 3 of the gasspace has an outlet 6. The gases enter through inlet 7 into the gasspace below the grate 2. v

The operation is as follows:

The hot gases entering through inlet 7 into the gas space 8 pass throughthe grate .l into and through the charge in the drying chamber 1. andabsorb water carried by the charge. The outlet 6 and the inlet 7 arepart of a gas circulating system (not shown) MATERIAL BY MEANS 0? FIREGASES.

Serial No. 713,623

including a combustion chamber and additional means for heating thecirculating gases. The vohune of gas leaving the drying chamber isgreater than the volume of as entering into it substantially by thevolume of water vapor absorbed from the charge, and the heat energy ofthe excess gas is always utilized to the fullestgsxtent even if the gasreturning to the circulating system through the outlet 6 should leavethe drying chamber at a temperature which is in excess of its saturationpoint. The excess gas passes into and through that part of the chargethat last enters the drying zone and passes together with moistureabsorbed out through the outlet 4.

The only closure at the top of the drying chamber is the column ofmaterial in the #harging shaft 1* which affords an effective sealagainst egress of gas. The arrangement described makes it unnecessary topass the excess gas out of the drying chamber through a layer of coldfresh charge whereby con densalion in the material to be dried of thewater vapor carried by the excess gas is avoided.

Any air that might enter through the charging shaft 1 is carried offtogether with the excess gas through flue 4 which according to theparticular conditions may be a draft flue or an ordinary outlet. Theapplication of a negative pressure or the degree thereof are matters ofjudgment. At any rate there are no special closures to be controlled.The rate of movement of the material and the rate of movement of thedehydrating gas through the drying chamher and the heating of the gas inthe circulation system may be varied to suit best the particularconditions.

In Fig. 2, the drying-chamber 9 has a central intake opening 14 throughwhich the material passes "from a hopper 14 and a central outlet opening17. Within the chamber 9 are disposed two grates 2 and 2" divergingdownwardly from a point sub stant ally centrally below the intakeopening 14 and. relatively close thereto. The material entering thechamber 9 is thus forced to divide, passing down over the two grateswhich together with the material define a gas space 9. The lower portionof the chan'iber 9 is funnel shaped whereby the iii) issuance materialafter passing over the two grates is directed toward the common outlet17. The dimensions of the intake opening is and outlet 17, the size anddisposition of the. grains 2 and E2", and the configuration I of thechamber 9 are so correlated that. the

material readily moves through the chainher. There is of courseconsiderable latitude in this respect. y

The gas space 9 is in communication with a tube 13 through which the gasot the circulating system enters the drying chamher. In the hoppercentrally above the intake l4: is a roof-shafted deflector element 1:)creating a gas space which is in communication with a tube 16 connectedwith the atmosphere.

liaterally of the intake opening 14 are spaces 11 and 12 which are notfilled by the material. These spaces are in communication tl'iroughpipes 11. and 12 with the circulating system (not shown).

The gas coming from the circulating system enters through the pipe 13and passes through the grates 2 and 2* into the gas spaces 11 and 12 andreturns laden with water-vapor absorbed from the material to thecirculating system. The excess gas must take its course through theintake opening 14c and following the path of least resistance flowstoward the gas space defined by the deflector 15 from which it is passedto the atmosphere. The hopper let is of such height that the column ofmaterial above the deflector affords an effective seal.

The deflector 15 hasbeen referred to merely as an example for creating agas space for allowing the excess gas to be drawn oil. The particularform and the disposition of the gas space are a matter of engineeringpractice susceptible to varia tion in many respects.

For the sake of simplicity the drying chamber has been shown as ofrectangularcross-section It may, of course, have any othercross-sectional configuration and the form of the grate may he changedcorrespondingly. k

The arrangements illustrated and described not only represent simpleconstructions for carrying out in simple manner the drying of material,but they are peculiarly adapted to minimize the danger of explosions inthe drying chamber and the detrimental effects thereof. The directconnection of the gas space 3 of the chamber 1;

with the atmosphere prevents the concentration oi a large volume of gasin the chamloer. The pressure can not reach such proportions s to doserious damage.

The communication between the gas space 3 and the atmosphere may hesuitably enlarged to carry oil gases suddenly evolved at such rate as isnecessary to obviate material damage.

The construction of Fig. 2 also may he modified to reduce the effect ofan explosion to safe limits.

While in the case of large openings in communication with the atmosphereany air that might cnterinto the gas space would be carried oil again bythe current of out going gases, it is of course a simple expedient toprevent the entrance of air by applying suitable means as for instance aliap valve l which while normally reducing the cll'cctive exit opening,may yield instan tancously to the pressure of gases evolved during anexplosion and allow the same to quickly pass to the atmosphere.

lVhat is claimed as the invention is:

1. In a process of drying material, the steps which consistinmaintaining a column of material by adding fresh material and removingdried material, passing drying gas into the column and removingmoisture-laden gas out of the column at substantially the same rate andseparately withdrawing the excess gas corresponding in volume to theamount of Water absorbed'by the drying in its passage through thematerial.

2. In a process of drying material, the steps which consist inmaintaining a column of material by adding; fresh material and removingdried material, passing drying gas into the column and removingmoisture-laden gas out of the column at substantially the same rate andseparately withdrawing the excess gas corresponding in volume to theamount of Water absorbed by the drying gas in its passage through thematerial, at points of the column in advance of the region at which themoisture-laden gases are withdrawn.

3. In a process ofdrying material the steps which consist in maintaininga, column of material by adding fresh material "nd removing driedmaterial, passing drying into the'column atone side thereof andwithdrawing .moistureladen gas from the col-- umn substantally at theopposite side thereof and separately withdrawing the excess gascorresponding in volume to the amount of Water absorbed by the dryinggas in its passage through the material at points of the column inadvance of the region at which the moisture-laden gases are withdrawn.

l. Process according to claim 1 in which the points of entrance of thedrying gas and the points of withdrawal of the gases are so chosen thatthe sections of the column at both ends thereof afford effective sealsagainst the ingress of sir or egress of gases respectively.

5. E pparatus for the drying of material, comprising a drying chamberhaving an inlet at the top and fll'l-OlIlllQl) at the bottom andincluding means for maintaining colllll) llll Lemma umns of materialabove the inlet and below the outlet respectively, a conduit for. passmgdrying gas into the chamber, a conduit for withdrawing moisture laden.gases out of the chamber and a separate conduit in comvrnunication witha region of the material in top of the chamber and an'outlet at the hot--to1n thereof including means for maintaining columns of materialabovethe inlet and below the outlet respectively, means for passinggasupwardly through the forami nous sl evvay and for withdrawing gas fromthe opposite surfaoeof the column and means for separately withdrawinggas at points of the column in advance of said surface" "Z. In a processof drying material, the steps which consist in. maintaining a movingcolumn of material to be dried by adding fresh material to one end. andremoving dried material from the other end thereof, passing drying gasinto a zone of said column intermediate the ends thereof, andWithdrawing the main portion of gas from points opposite the points ofadmission and the excess gas from points in the column in advance ofsaid first mentioned points.

In testimony whereof, I alfix .my signature GEORG MULLE

